The present invention relates to shell and tube heat exchangers for refrigeration systems and more particularly relates to waterboxes for such shell and tube heat exchangers.
Many refrigeration systems have shell and tube heat exchangers wherein the tubes extend through tube sheets which form the ends of the shell, and wherein tube support sheets are used in the shell to further support the tubes. Usually, water is passed through the tubes which are in thermal contact with a refrigerant flowing through the shell side of the heat exchanger. Normally, a waterbox is attached to a tube sheet at one end of the heat exchanger to enclose the ends of the tubes extending through the tube sheet and to supply and direct the flow of water through the tubes of the heat exchanger. Another box is attached to the tube sheet at the other end of the heat exchanger to enclose the ends of the tubes extending through this tube sheet to provide a complete fluid flow circuit through the heat exchanger. Typically, there is at least one partition in the water supply waterbox dividing this waterbox into a first section having a first group of heat exchanger tubes and a second section having a second group of heat exchanger tubes. Water is supplied to the waterbox through a water supply conduit connected to a nozzle on the waterbox which forms a fluid flow circuit with the first group of tubes in the first section of the waterbox. The water supplied to the waterbox flows through the first group of tubes to the opposite end of the heat exchanger and is returned through the second group of tubes to the second section of the waterbox. A water return conduit is connected to a nozzle on the waterbox which forms a fluid flow circuit with the second group of tubes in the second section of the waterbox and the water is directed out of the waterbox through this return conduit. If desired, more than two passes of the water through the heat exchanger may be obtained by using more partitions dividing the tubes into several distinct, interconnected groups.
To clean or inspect the tubes in the heat exchanger, or for other such purposes, it is necessary to gain access to the interiors of the tubes. Conventionally, in order to provide access to the interiors of the heat exchanger tubes, the nozzle connections to the waterbox are made through a side wall of the waterbox, which is normally a curved shape, so that an end cover of the waterbox may be removed thereby exposing the ends of the tubes. The nozzle connections are made through the side wall so that access to the heat exchanger tubes is obtained without having to disturb the nozzle connections to the waterbox. This type of waterbox is known as a marine waterbox. However, marine waterboxes are relatively difficult and costly to manufacture because of the inherent complexity in making nozzle connections through a curved side wall and because of the necessity to provide relatively large side walls to accommodate the nozzle connections.
A simpler and less costly waterbox is provided by making the nozzle connections to the waterbox through the end cover of the waterbox because the end cover is usually flat. However, the water supply and return conduits must be disconnected from the waterbox nozzles before the cover can be removed to gain access to the interiors of the heat exchanger tubes. This is undesirable because it is usually difficult and cumbersome to disconnect the conduits.